package Homework1;

import java.util.Scanner;

public class Homework1_3 {
    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);
        int grade = input.nextInt();
        if (grade > 100 || grade < 0)
            System.out.print("Data is error");
        else{
            int gra = grade / 10;
            System.out.print("Grade is ");
            switch (gra){
                case 10:
                case 9:System.out.println("A");break;
                case 8:System.out.println("B");break;
                case 7:System.out.println("C");break;
                case 6:System.out.println("D");break;
                default:System.out.println("F");break;
            }
        }
    }
}
